A manufacturing machine for producing combination cigarette filters comprises a group-forming unit that forms groups of filter portions, each comprising at least two different filter portions aligned axially and contacting at the ends; a winding unit which receives a succession of groups of filter portions from the group-forming unit, winds a strip of wrapping material about the succession of groups of filter portions to form a continuous filter rod, and cuts combination filters from the continuous filter rod by cyclically cutting the continuous filter rod transversely; and a transfer unit which transfers the groups of filter portions from the group-forming unit, in which the groups of filter portions travel transversely (i.e. perpendicular to their central axes), to the winding unit, in which the groups of filter portions travel axially (i.e. parallel to their central axes). Because it receives the groups of filter portions travelling transversely, and releases them travelling longitudinally, the transfer unit must therefore alter the travelling mode of the groups of filter portions.
Known transfer units normally comprise a drum having a number of horizontal suction seats rotated, parallel to themselves, about a central axis of rotation. The drum, known as and hereinafter referred to as a “spider”, feeds the groups of filter portions successively into a forming beam of the winding unit.
Known transfer units also comprise at least one release drum for releasing the groups of filter portions successively to the spider. One example of a transfer unit of the above type is described in Patent Application EP1787534A1.
To meet changing market demand, a modern manufacturing machine must be able to produce a range of combination cigarette filters, which means brand changes are relatively frequent to change the machine over to the manufacture of a different type of combination cigarette filter. Very often, the new combination cigarette filter to be produced on the manufacturing machine differs in length from the previously produced type, thus resulting in a difference in the length of the groups of filter portions, and inevitably in necessary alterations to the transfer unit. In particular, a brand change may call for adjusting/changing mechanical parts (e.g. the cams or suction seats) of the spider and/or of the release drum. On known manufacturing machines, however, adjusting/changing mechanical parts of the spider and particularly of the release drum is extremely complicated and time-consuming, on account of meshing of the spider seats and release drum seats seriously limiting access to the spider and particularly to the release drum.